Do you believe in ghosts?

My friend sent me this picture that she took. This is her note, "ok so i went to fort pulaski is savannah and i took this picture when i was in the part of the fort that was used as a jail. When i took this pic i was with other people but i waited for them to move behind me so i could take a decent picture BUT you can clearly see that in the one door way there is someone standing there even though im positive no one was there when i took it. You have to zoom in on it to really see that it kinda looks like a soldier, at least to me it does." it looks real to me!